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Subject[PATCH 5.10 343/663] perf tools: Fix DSO filtering when not finding a map for a sampled address
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit c69bf11ad3d30b6bf01cfa538ddff1a59467c734 ]

When we lookup an address and don't find a map we should filter that
sample if the user specified a list of --dso entries to filter on, fix
it.

Before:

$ perf script
sleep 274800 2843.556162: 1 cycles:u: ffffffffbb26bff4 [unknown] ([unknown])
sleep 274800 2843.556168: 1 cycles:u: ffffffffbb2b047d [unknown] ([unknown])
sleep 274800 2843.556171: 1 cycles:u: ffffffffbb2706b2 [unknown] ([unknown])
sleep 274800 2843.556174: 6 cycles:u: ffffffffbb2b0267 [unknown] ([unknown])
sleep 274800 2843.556176: 59 cycles:u: ffffffffbb2b03b1 [unknown] ([unknown])
sleep 274800 2843.556180: 691 cycles:u: ffffffffbb26bff4 [unknown] ([unknown])
sleep 274800 2843.556189: 9160 cycles:u: 7fa9550eeaa3 __GI___tunables_init+0xf3 (/usr/lib64/ld-2.32.so)
sleep 274800 2843.556312: 86937 cycles:u: 7fa9550e157b _dl_lookup_symbol_x+0x4b (/usr/lib64/ld-2.32.so)
$

So we have some samples we somehow didn't find in a map for, if we now
do:

$ perf report --stdio --dso /usr/lib64/ld-2.32.so
# dso: /usr/lib64/ld-2.32.so
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'cycles:u'
# Event count (approx.): 96856
#
# Overhead Command Symbol
# ........ ....... ........................
#
89.76% sleep [.] _dl_lookup_symbol_x
9.46% sleep [.] __GI___tunables_init
0.71% sleep [k] 0xffffffffbb26bff4
0.06% sleep [k] 0xffffffffbb2b03b1
0.01% sleep [k] 0xffffffffbb2b0267
0.00% sleep [k] 0xffffffffbb2706b2
0.00% sleep [k] 0xffffffffbb2b047d
$

After this patch we get the right output with just entries for the DSOs
specified in --dso:

$ perf report --stdio --dso /usr/lib64/ld-2.32.so
# dso: /usr/lib64/ld-2.32.so
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'cycles:u'
# Event count (approx.): 96856
#
# Overhead Command Symbol
# ........ ....... ........................
#
89.76% sleep [.] _dl_lookup_symbol_x
9.46% sleep [.] __GI___tunables_init
$
#

Fixes: 96415e4d3f5fdf9c ("perf symbols: Avoid unnecessary symbol loading when dso list is specified")
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20210128131209.GD775562@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/event.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 05616d4138a96..7e440fa90c938 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -673,6 +673,8 @@ int machine__resolve(struct machine *machine, struct addr_location *al,
}

al->sym = map__find_symbol(al->map, al->addr);
+ } else if (symbol_conf.dso_list) {
+ al->filtered |= (1 << HIST_FILTER__DSO);
}

if (symbol_conf.sym_list) {
--
2.27.0


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